Froth-flotation concentration of ores



Patented 17, 1929 UNITED-STATES PATENT OFFICE CORNELIUS H. KELLER, OF SAN FRANCISCO, CALIFORNIA, ASSIGNOR TO MINERALS SEPARATION NORTH AMERICAN CORPORATION, OF NEW YORK, N. Y., A COR- PORATION OF MARYLAND IROTH-FLOTATION CONCENTRATION OF ORES No Drawing.

" and may involve considerable loss 0 valuable mineral which is dropped indropping the iron.

According to the present invention a sulphur-containing organic compound is used which is a sulphh dric derivative of a hydrocarbon and whic in examples given below shows a marked effect in cooperatin with many mineral-frothing agents in facihtating the flotation of the more valuable mineral in 5 a richer concentrate and also in minimizing T the flotation of the iron. The invention is herein disclosed in some detail as carried out with ethyl sodium mercaptide, which is a fairly stable crystalline compound, and with para-thio-cresol, with thio-beta-naphthol, with thio-phenol, and with benzyl mercaptan. Another sulphhydric derivative of.a hydrocarbon, to wit, ethyl mercaptan itself, has also been found to be an effective reagent for the same purposes.

Other features and advantages will hereinafter appear.

Various methods may be found suitable for the commercial preparation of mercaptides, but for the work described herein sodium ethyl mercaptide was prepared by adding metallic sodium to ethyl mercaptan. Mercaptans may be regarded as substituted alcohols, containing sulphur instead of oxygen,

thus ethyl mercaptan is C H SH. A mercaptide may be regarded as a mercaptan in which the sulphhydric hydrogen is replaced by a metal as in sodium ethyl mercaptide C,H,SNa.-

Application filed January 11, 1923. Serial No. 80,886

The following are examples wherein ethyl mercaptide was used:

Example 1.Utah copper ore already ground was further ground for five minutes 1n a-laboratory ball mill with sixpounds of lime, measured as calcium oxide, per ton of ore, and was then made into a pulp with the requisite amount of water and agitated for eight minutes in a minerals separation spitzkasten subaeration testing machine with 0.24 pounds of sodium ethyl mercaptide per ton of ore and with one-tenth of a pound of hardr wood creosote per ton of ore. The concentrate was separated in the formof a froth and was reagitated with the further addition of three-tenths of a pound of hardwood creosote per ton of ore. The results are shown in the following table: I

Assays Recoveries Wt. Cu Fe u F0 goods--- 100.0 onc 19. 6 Midd 1.6 6 0. ed 3 e. 2 3 10. 5} 9 4. 1} 6 all 96. 4 18 2. 1 17. 1 76. 4

Example 23.-A four-charge cycle test on another sample of Utah ore showed that there was no-tendenc to build up either iron or copper in the middlings. The same reagents were used in slightly different quantities, to wit, sodium mercaptide 0.22 ounds per ton, hardwood creosote 0.15 pounds treated as before to yield a finished concentrate and a middlin A' third charge and thereafter a fourth c arge were each treated as above described. The concentrates of the four charges were united and assayed as a single pro not.

per ton, lime, A as CaO, six pounds per ton. This yielded a The results are shown in the following Example 3.A test similar to the first example was carried out with a much smaller amount of sodium ethyl mercaptide. In this test the agitation with lime in the ball mill was the same, the first agitation in the flotation machine was with 0.04 pounds of sodium j ethylmercaptide and 0.2 pounds of hardwood creosote, all per ton of ore, for eight minutes. The concentrate obtained by this treatment was reagitated for three minutes with a further addition of 0.2 pounds of hardwood creosote per ton of original ore. The results are shown in the following table,

showing a lower recovery but which was off-- set by a higher grade ofconcentrate and an increased rejection of the iron.

Assays Recoveries Wt. Cu Fe Cu Fe g88dS.. 101 1.2 5% 22.60 100.0 103.0 one .3 53.8 1 .1 Mi'dd }a4 }21.9s m 1 21 }71.9 has ran 96.6 .30 22 2&1 81.5

Large rejection of the iron of the ore and rlchness of the concentrate brought about by the use of a mercaptide are illustrated in the following test of Engels copper ore.

Example 4.-The ore was ground fifteen minutes in a laboratory ball mill, and then was made into a pulp and agitated for ten minutes with 2.5 pounds of tri-sodium phosphate (enough to make the pulp alkaline), 0.12 pounds of sddiumethyl inercaptide, and 0.2 pounds of hardwood creosote, all per ton of ore. The resulting froth concentrate was reagitatedwith 0.3 pounds of hardwood creosote per ton of original ore. The results are shown in the following table:

Assays Recoveries Wt. Cu Fe Cu Fe gems---" 100. 11 10. 100.'0 onc 3. 33 1 .3 3 5.6 M11111 22d 6 ml 10.2} 6 10 6} 2. ch Tall 93.3 30 9.7 15 7 91 5 The complex and refractory silver-leadzlnc iron-bearing ore of the San Francisco mlnes of Mexico yielded rich lead and zinc concentrates relatively free from iron when concentrated with sodium ethyl mercaptide.

Ewample 5.The ore was ground for fifteen minutes in a ball mill with half a pound of sodium sulphide per ton of ore. It was then made into a pulp and agitated for seven minutes with three pounds of soda ash, 0.04 pounds of sodium mercaptide, 0.3 pounds of Barrett N o. 634 oil, and 0.15 pounds of cresylic acid, all per ton of ore, and a lead-bearing froth was separated. The remainder of the ore pulp was then further agitated for ten minutes with the addition of one-half pound of copper sulphate, 0.1 pounds of sodium mercaptide, 0.3 pounds of Barrett No. 634 oil, and 0.2 pounds of steam distilled pine oil, all per ton of ore, and a zinc-bearing froth separated. The above lead concentrate was separated into a finished concentrate and a middling by reagit-ation for five minutes with "0.2 pounds of cresylic acid per ton of original in the following table:

Assays Wt. Ag.oz.p. t. Pb Zn Fe 52 5* %;3 i? 132 iii 3% one.-- 6

a: 1- 2 8 a? a 22 n 0110-.. Zn Middc. 0 2a 8} s. 0} 7 2s. 2} 2 10. 4} 7 'Tail- 45.4 6.2 1.6 5.4 5.4

Recoveries Ag Pb Zn Fe Heads 100.0 100. 0 100.0 100. 0 Pb Oonc 30. 9 61. 9 7. 6 7. 0 Pb Midi... 19. 7 18.7 12.1 11.2 Zn Cone 30.0 8. 7 63. 2 35. 2 Zn Midd 6. 2 3. 5 6.1 9. 3 Tail 13. 2 7. 2 11. 0 37. 3

It wasfound that sodium mercaptide a week old gave nearly the same results as the fresh material.

Extraordinarily complete concentrations have been accompanied by a very large rejection of the iron, as in the following test of California rand ore.

Ewam-ple 6'.The ore was ground in a ball mill for twenty minutes with 3.3 pounds trona (a natural alkali) per ton of ore, and then made into a pulp with water and ag ltated for fifteen minutes with 0.17 pounds of sodium ethyl mercaptide, 0.33 pounds of coal tar creosote, and 0.17 pounds of steam distilled pine oil, all per ton of ore. The froth concentrate thus obtained was reagitated, for

four minutes with the further addition of 0.04 pounds of steam distilled pine oil per ton of original .ore and yielded a finished concentrate and a middling. The results are shown in the following table:

It has been found that a sulphhydric derivative of a hydrocarbon is a useful flotation agent in acid and neutral pulps as well as in the alkaline pulps of the above examples.

Ewample 7'.Ore of the Allenby Copper Company of British Columbia, contaimng bornite as the principal copper mineral, was reground for twenty minutes in a ball mill,

made into a pulp with water, and agitated M 1 with 0.11 pounds of sodium ethyl mercaptide and one-tenth of a pound of cresylic acid, both per ton of ore,- and yielded a finished concentrate. The-results are shown in the following table:

Assays- Recoveries Product Wt. Cu Fe ,Cu Fe Heads 100. 0 1. 88 4. 3a 100. 0 100. 0 Cone 5. 3 27. 92 10. 8 -78. 7 13. 1 T811 94. 7 0. 42 4. 0 21.3 86. 9

Assays Recoveries Product 1% Fe% 011% Fe% Heads 100. 0 1. 33 4. 08 100. 0 100. 0 Cone 13. 4 9. 04 2A. 6 91. 0 80. 9 Tail. 86. 6 0. 14 9 9. 0 19. 1

It has also been found that a sulphhydric derivative of a hydrocarbon is a useful flotation agent when used with such a flotation agent as sodium silicate. It isat times advanta eous to add the sodium silicate before the other reagents are added, although this may require a larger quantity of sodium silicate. This procedure has been found to be especially useful in concentrating a coped pine 011 T per ore in which a substantial the copper is oxidized.

Exam Ze .9..-Inspiration ore containing a substantial proportion of oxidized cop erwas reground for twenty minutes in a all mill and then made into a pulp with Water, and 1.5 pounds of sodium silicate were added to the pulp and mixed therewith. Then were added 0.22 pounds of sodium ethyl mercaptide, 0.6 pounds of hardwood creosote and 0.2 pounds of Barrett coal tar creosote, all per ton of ore, and the pulp agitated for twenty minutes to form a rougher froth concentrate. This concentrate was reagitated for five minutes with half a pound of sodium silicate per ton of original ore, to form a finished concentrate and a middling. The results are shown in the following table:

proportion of Assays Recoveries Wt.% 011% 5 Fe% 011% 5 12% Heads.. 100.0 0.89 0.22 1.31 100.0 100.0 100.0 Conc 1.4 37.42 0.68 20.4 58.4 4.5 16.0 4.1 3.22 0.54 6.4 16.9 9.1 16.6 Tall-. 03.9 0.24 0.20 1.3 24.7 86.4 61.4

In the following example phenol mercaptan or thiophenol was used:

Ewaxmple 10.Impact screen undersize of Utah copper ore was reground with 6 pounds of calcium oxide and with 0.4 pounds of thiophenol, both per ton of the material treated, and was then made into a pulp with water and agitated for ten minutes with 0.4 pounds of dark cres lic acid per ton, and a froth concentrate col ected. The results are shown in the following table:

Assays Recoveries Product Wt. Cu Fe Cu Fe Heads 100. 0 1. 25 1. 36 100. 0 100. 0 Cone 4. 42 25. 78 13.5 90. 8 43. 8 all 95 58 12 0. 8 9. 2 56. 2

In the following example thio-beta-naphthol was used:

Example 11.Impact' screen undersize of Utah copper ore was reground' with 6 pounds of calcium oxide and 0.4 pounds of thio- 'beta-naphthol, both er ton of material treated, and was then ma e into a pulp with water and agitated for ten minutes with 0.55 pounds of dark cresylic acid per ton and a froth concentrate collected. The results are shown in the following table:

Assays Recoveries Product Wt. Cu Fe Cu Fe Heads 100. 0 1. 26 1. 51 100. 0 100. 0 Cone 4. 51 23. 76 14. 4 84. 8 43. 0 Tail 95. 49 20 0.9 15. 2 57. 0

Nearly as good results were obtained when the thio-phenolor para-thio-cresol or thiobeta-naphthol were added to the pulp instead of to the material while being ground, although the concentrates Were'not so rich in copper as when the thio agent was added in the grinding mill.

When potassium phenol mercaptide was substituted for potassium phenol mercaptan or thio-phenol the results of the operation were superior to results obtained in a parallel test wherein it was absent. Similarly, when potassium cresol mercaptide was substituted for potassium cresol mercaptan or thio-cresol the results of the operation were superior to results obtained 1n a parallel test wherein it was absent.

In the following example benzyl mercaptan was used with a copper ore wherein the iron constituent was negligible:

Example 13.Anaconda table tailings, mesh, were made into a pulp with water and pre-agitated for half a minute in a neutral pulp with 0.32 pounds of pine oil and 0.58 pounds of benzyl mercaptan, both per ton of solids, and then further agitated to yield a froth-concentrate which was separated for three minutes. The results are shown in the following table:

Cu Heads 1.28 Cones. 7 .44 Recovery 90.1% Tails. 0.15

Having now particularly described certain embodiments of my invention, 1 claim:

1. The process of concentrating an ore containing a mineral value and gangue, which consists in agitating a suitable pulp of the ore containing sodium ethyl mercapt1de so as to produce a mineral-value-bearing froth, and

separating the froth.

2. The process of concentrating an ironbearing ore containing a mineral value and gangue, which consists in agitatin a suitable pulp of the ore with sodium ethyl mer- 4. A method of effecting the concentration of minerals by flotation, which comprises subjecting the mineral pulp to a froth flotation operation in the presence of a nitrogen-free thioalcohol.

5. A process of concentrating ores by flotation which comprises adding to the ground ore a flotation reagent, com rising a compound of the general type R -R, in which R stands for an alkyl radical and R stands for a metal or hydrogen, and subjecting the mixture to a froth flotation operation.

6. A process of concentrating oresby flotation, which comprises subjecting a pulp of an ore of the mineral to be concentrated to froth flotation in the presence of a mercaptan of the general type RS-H in which R stands for a non-nitrogenous organic radical.

7. The process of concentrating an ore containing a mineral value and gangue, which comprises subjecting a pulp of the ore to froth flotation in the presence of a suphhydric derivative of a hydrocarbon of the general type RSR, in which R stands for an oxygen-free organic radical, and R stands for a metal or hydrogen.

8. The process of concentrating an ore containing a mineral value and gangue, which comprises subjecting a pulp of the ore to froth flotation in the presence of a suphhydric derivative of an aliphatic alkyl goup of the general type RSR, in which stands for an oxygen-free organic radical and R stands for a metal or hydrogen.

9. A process of concentrating ores by flotation which comprises adding to the ground ore a flotation reagent comprising ethyl mercaptan and subjecting the mixture to a froth flotation operation.

10. A process of concentrating ores by fiotation, which comprises adding to the ground ore a flotation reagent, comprising a compound of the general type RSR, in which R stands for the ethyl group and R stands for a metal or hydrogen.

11. The process of concentrating an ironbearing ore containing a mineral value and gangue, which consists in agitating a suitable pulp of the ore with a sulphhydric derivative of a hydrocarbon of the general type RSR in which R stands for an oxygenfree organic radical and R stands for a metal or hydrogen, so as to form a froth containing a large proportion of a value and a diminished proportion of the iron of the ore, and separating the froth, 

